Quote:
Originally Posted by moparrob
I suppose if you want to split hairs down to the transitional surface of the tapering cones of a 108 jet drilled to 117 vs. a standard 117 jet there probably is some infinitesimal difference on that surface. However, there was already a taper on the 108 jet and the orifice was only opened up .004", about the size of a hair.
Anyhow, I'm not looking to debate something which I really have no expertise in. I'm just searching for practical answers to get an inexpensive Chinese motorcycle to run smooth without hiccups.
All positive input is appreciated.
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Aside from the transitional, the drilled hole is unlikely to be as smooth as a factory made one and can be crooked or otherwise imperfect. I've seen jets drilled and go leaner. The other caveat is that using a .046" bit doesn't guarantee a .046" hole. Bit and chuck quality, how the jet is secured, how the drilling is executed, whether the hole is de-burred, etc.; all can lead to different results.
I'm not knocking the practice, I've drilled fuel and nitrous jets many times, it just can't be reliably compared to a factory made jet's flow potential. This doesn't matter since you're tuning for yourself, it's just not a reliable recipe for someone else to follow.